U.S. patent application number 15/303035 was filed with the patent office on 2017-02-02 for process and device for removing water and/or oxygen from organic liquid.
The applicant listed for this patent is ExxonMobil Patents Inc.. Invention is credited to Christopher L. Becker, John R. Porter, Jonathan J. Watts.
Application Number | 20170028312 15/303035 |
Document ID | / |
Family ID | 51265626 |
Filed Date | 2017-02-02 |
United States Patent
Application |
20170028312 |
Kind Code |
A1 |
Becker; Christopher L. ; et
al. |
February 2, 2017 |
Process and Device for Removing Water and/or Oxygen from Organic
Liquid
Abstract
A process and a device for removing water and/or oxygen from a
crude organic liquid stream using a distillation column with heat
input and dry nitrogen stream. A side effluent stream comprising
water at a high concentration is drawn from the distillation
column. An optional settling drum can be used to separate the
aqueous phase from the organic phase in the side effluent stream
can be used. The invention can be advantageously used for purifying
a crude organic liquid stream comprising one or more of benzene,
toluene, xylene, ethylbenzene, cumene, cyclohexane, cyclohexene,
cyclohexanol, cyclohexanone, and the like.
Inventors: |
Becker; Christopher L.;
(Manhattan, KS) ; Porter; John R.; (Lake City,
MI) ; Watts; Jonathan J.; (Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ExxonMobil Patents Inc. |
Baytown |
TX |
US |
|
|
Family ID: |
51265626 |
Appl. No.: |
15/303035 |
Filed: |
March 19, 2015 |
PCT Filed: |
March 19, 2015 |
PCT NO: |
PCT/US2015/021530 |
371 Date: |
October 10, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62005470 |
May 30, 2014 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C07C 7/04 20130101; B01D
3/143 20130101; B01D 3/346 20130101; C10G 33/00 20130101; C10G 7/00
20130101; C07C 7/05 20130101; C07C 15/04 20130101; C10G 7/04
20130101; C07C 7/05 20130101 |
International
Class: |
B01D 3/34 20060101
B01D003/34; B01D 3/14 20060101 B01D003/14; C07C 7/04 20060101
C07C007/04 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 6, 2014 |
EP |
14180063.1 |
Claims
1. A process for removing water and/or oxygen from a crude organic
liquid stream, the process comprising: (I) feeding the crude
organic liquid stream into a distillation column at a first
location on a side of the distillation column; (II) feeding a
stream of dry nitrogen gas into the distillation column at a second
location on the side below the first location; (III) drawing a side
effluent stream comprising water at a concentration higher than in
the crude organic liquid stream at a third location on the side
between the first location and the second location; (IV) drawing a
gas effluent stream comprising nitrogen, oxygen, and organic vapor
from a fourth location in the vicinity of the top of the
distillation column; (V) providing heat to the liquid in the
distillation column at a fifth location in the vicinity of the
bottom of the distillation column; and (VI) drawing a purified
organic liquid stream comprising at least one of water and oxygen
at a concentration lower than in the crude organic liquid stream
from a sixth location in the vicinity of the bottom of the
distillation column.
2. The process of claim 1, further comprising: (VII) introducing at
least a portion of the side effluent stream into a settling vessel;
(VIII) obtaining an upper organic phase and a lower aqueous phase
in the settling vessel; and (IX) recycling at least a portion of
the organic phase to the distillation column.
3. The process of claim 2, wherein in step (IX), at least a portion
of the organic phase is recycled to the distillation column at a
seventh location located in a range from the first location to the
third location.
4. The process of claim 1, wherein the crude organic liquid stream
comprises benzene at a concentration of at least 95 wt %, based on
the total weight of the crude organic liquid stream.
5. The process of claim 1, wherein: the crude organic liquid stream
comprises water at a concentration of Cw1 ppm, and oxygen at a
concentration of Cox1 ppm, based on the total weight of the crude
organic liquid stream, where 10.ltoreq.Cw1.ltoreq.1000, and
0.1.ltoreq.Cox1.ltoreq.20.
6. The process of claim 5, wherein the purified organic liquid
stream comprises water at a concentration of Cw2 ppm, and oxygen at
a concentration of Cox2, based on the total weight of the purified
organic liquid stream, where 0.1.ltoreq.Cw2.ltoreq.50, and
0.01.ltoreq.Cox2.ltoreq.5.
7. The process of claim 1, wherein the purified organic liquid
stream comprises water at a concentration of Cw2 ppm, and oxygen at
a concentration of Cox2, based on the total weight of the purified
organic liquid stream, where 5.ltoreq.Cw1/Cw2.ltoreq.1000, and
5.ltoreq.Cox1/Cox2.ltoreq.100.
8. The process of claim 1, wherein the side effluent stream
comprises water at a concentration of Cw3 wt %, based on the total
weight of the side effluent stream, where
0.01.ltoreq.Cw3.ltoreq.20.
9. The process of claim 1, wherein the crude organic liquid stream
in step (I) has a temperature in a range from 8.degree. C. to
60.degree. C.
10. The process of claim 1, wherein the purified organic liquid
stream in step (VI) has a temperature in a range from 20.degree. C.
to 75.degree. C.
11. The process of claim 1, wherein the side effluent stream in
step (III) has a temperature in a range from 15.degree. C. to
50.degree. C.
12. The process of claim 1, wherein at least a portion of the gas
effluent stream in step (IV) is delivered to a combustor.
13. The process of claim 1, further comprising: (X) measuring the
temperature inside the distillation column at the height of the
third location; and (XI) controlling the amount of heat provided in
step (V) based on the temperature measured in step (X).
14. The process of claim 1, wherein in step (V), the heat is
provided by steam through a heat exchanger.
15. The process of claim 1, wherein the distillation column has a
total number of theoretical trays of N(1) from the top to the
bottom, where 5.ltoreq.N(1).ltoreq.15.
16. The process of claim 15, wherein the number of theoretical
trays from the third location to the fourth location is N(2), where
1/12N(1).ltoreq.N(2).ltoreq.2/3N(1).
17. The process of claim 16, wherein 3.ltoreq.N(2).ltoreq.5.
18. The process of claim 1, wherein the absolute pressure inside
the distillation column at the fourth location is in a range from
Pam-50 kPa to Pam+50 kPa, where Pam is the pressure of ambient
air.
19. A device for removing water and/or oxygen from a crude organic
liquid stream, comprising a distillation column shell, packing
material and/or trays housed inside the distillation column shell,
and the following: (A) a first inlet on the shell at a first
location on a side of the distillation column configured for
accepting the crude organic liquid stream into the distillation
column; (B) a second inlet on the shell at a second location on the
side below the first location configured for accepting a stream of
dry nitrogen gas into the distillation column; (C) a first outlet
on the shell at a third location on the side between the first
location and the second location configured for drawing a side
effluent stream comprising water at a concentration higher than in
the crude organic liquid stream; (D) a second outlet at a fourth
location on the shell in the vicinity of the top of the
distillation column configured for drawing a gas effluent stream
comprising nitrogen, oxygen, and benzene; (E) a heat exchanger
configured for providing heat to the liquid in the distillation
column at a fifth location in the vicinity of the bottom of the
distillation column; (F) a third outlet at a sixth location on the
shell in the vicinity of the bottom of the distillation column
configured for drawing a purified organic liquid stream having
lower concentrations of water and oxygen than the crude organic
liquid stream; and (G) a settling vessel configured for accepting
at least a portion of the side effluent stream, allowing fluid
therein to separate to form an upper organic phase and a lower
aqueous phase.
20. (canceled)
21. The device of claim 19, wherein the device further comprises:
(H) a third inlet on the shell at a seventh location between the
first location and the third location configured for accepting at
least a portion of the organic phase recycled to the distillation
column; and (I) a conduit configured for delivering at least a
portion of the upper organic phase to the third inlet.
22. The device of claim 19, further comprising: (J) a temperature
sensor configured for measuring the temperature of the distillation
column at the height of the third location; and (K) a controller
configured to control the amount of heat provided by the heat
exchanger based on the temperature measured by the temperature
sensor.
23. The device of claim 19, wherein the distillation column has a
total number of theoretical trays of N(1) from the top to the
bottom, where 5.ltoreq.N(1).ltoreq.15.
24. The device of claim 23, wherein the number of theoretical trays
from the third location to the fourth location is N(2), where
1/12N(1).ltoreq.N(2).ltoreq.2/3N(1).
25. The device of claim 24, wherein 3.ltoreq.N(2).ltoreq.5.
Description
PRIORITY CLAIM
[0001] This application claims priority to U.S. Provisional
Application Ser. No. 62/005,470, filed May 30, 2014, and EP
Application No. 14180063.1, filed Aug. 6, 2014, the disclosures of
which are fully incorporated herein by reference.
FIELD
[0002] The present invention relates to processes and devices for
purifying crude organic liquid streams. In particular, the present
invention relates to processes and devices for removing water
and/or oxygen from crude organic liquid streams. The invention is
useful, e.g., in purifying benzene used in processes for making
phenol and/or cyclohexanone.
BACKGROUND
[0003] Many chemical processes involve feeding an organic liquid
stream to a chemical reactor. Raw feed materials may have to be
purified to remove various impurities such as water and molecular
oxygen before being fed to the chemical reactor.
[0004] For example, benzene is a basic industrial chemical used as
a feed material in processes for making many other basic chemicals,
such as phenol, cyclohexanone, cyclohexane, cyclohexene,
cyclohexanol, xylene, and cumene. Two common impurities are water
and molecular oxygen, which can enter the benzene feed during
storage and transportation on exposure to the storage tanks and
ambient air. Under extreme conditions, the benzene feed may become
saturated by water and oxygen after long exposure to the ambient.
In many of these processes, a catalyst sensitive to impurities in
the benzene feed is used, and the presence of water and oxygen at
high concentrations can lead to undesirable side reactions
producing byproducts, which can poison the catalyst as well. To
achieve and maintain high performance of the catalyst in many of
these processes, it is highly desirable to reduce the water and/or
oxygen concentrations in the benzene feed to acceptable levels.
[0005] Particularly, in the process for making cumene from benzene
via propylene alkylation, a solid acid alkylation catalyst is
typically used. The solid acid can be an aluminosilicate molecular
sieve such as a zeolite of the MWW frame work, which is sensitive
to water and oxygen. Moreover, oxygen and water can react with
propylene, resulting in byproducts that can reduce catalyst
performance. Likewise, in the process for making cyclohexylbenzene
from benzene via hydroalkylation, a bi-functional catalyst
comprising a hydrogenation metal component such as Pd and a solid
acid component such as an aluminosilicate molecular sieve (e.g., a
zeolite of the MWW frame work) may be used. Water and oxygen
content in the benzene feed used in this process is desirably low
as well.
[0006] Existing processes for removing water and oxygen from crude
organic liquid streams such as crude benzene streams suffer from
one or more of the drawbacks of high energy consumption, high
material and equipment costs, and high benzene feed temperature at
high concentration of molecular oxygen leading to oxidation of
benzene by the dissolved oxygen.
SUMMARY
[0007] The present disclosure provides an alternative method and
device for removing water and oxygen from crude organic liquid
streams such as crude benzene streams addressing the above
problems.
[0008] A first aspect of the present disclosure relates to process
for removing water and/or oxygen from a crude organic liquid
stream, the process comprising:
[0009] (I) feeding the crude organic liquid stream into a
distillation column at a first location on a side of the
distillation column;
[0010] (II) feeding a stream of dry nitrogen gas into the
distillation column at a second location on the side below the
first location;
[0011] (III) drawing a side effluent stream comprising water at a
concentration higher than in the crude organic liquid stream at a
third location on the side between the first location and the
second location;
[0012] (IV) drawing a gas effluent stream comprising nitrogen,
oxygen, and organic vapor from a fourth location in the vicinity of
the top of the distillation column;
[0013] (V) providing heat to the liquid in the distillation column
at a fifth location in the vicinity of the bottom of the
distillation column; and
[0014] (VI) drawing a purified organic liquid stream comprising at
least one of water and oxygen at a concentration lower than the
crude organic liquid stream from a sixth location in the vicinity
of the bottom of the distillation column.
[0015] A second aspect of the present disclosure relates to a
device for removing water and/or oxygen from a crude organic liquid
stream, comprising a distillation column shell, packing material
and/or trays housed inside the distillation column shell, and the
following:
[0016] (A) a first inlet on the shell at a first location on a side
of the distillation column configured for accepting the crude
organic liquid stream into a distillation column;
[0017] (B) a second inlet on the shell at a second location on the
side below the first location configured for accepting a stream of
dry nitrogen gas into the distillation column;
[0018] (C) a first outlet on the shell at a third location on the
side between the first location and the second location configured
for drawing a side effluent stream comprising water at a
concentration higher than in the crude organic liquid stream;
[0019] (D) a second outlet at a fourth location on the shell in the
vicinity of the top of the distillation column configured for
drawing a gas effluent stream comprising nitrogen, oxygen, and
benzene;
[0020] (E) a heat exchanger configured for providing heat to the
liquid in the distillation column at a fifth location in the
vicinity of the bottom of the distillation column; and
[0021] (F) a third outlet at a sixth location on the shell in the
vicinity of the bottom of the distillation column configured for
drawing a purified organic liquid stream having lower
concentrations of water and oxygen than the crude organic liquid
stream.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a schematic diagram illustrating an example of the
process and device according to the present disclosure for removing
water and/or oxygen from a crude organic liquid stream.
DETAILED DESCRIPTION
[0023] Various specific embodiments, versions and examples of the
invention will now be described, including preferred embodiments
and definitions that are adopted herein for purposes of
understanding the claimed invention. While the following detailed
description gives specific preferred embodiments, those skilled in
the art will appreciate that these embodiments are exemplary only,
and that the invention may be practiced in other ways. For purposes
of determining infringement, the scope of the invention will refer
to any one or more of the appended claims, including their
equivalents, and elements or limitations that are equivalent to
those that are recited. Any reference to the "invention" may refer
to one or more, but not necessarily all, of the inventions defined
by the claims.
[0024] In the present disclosure, a process is described as
comprising at least one "step." It should be understood that each
step is an action or operation that may be carried out once or
multiple times in the process, in a continuous or discontinuous
fashion. Unless specified to the contrary or the context clearly
indicates otherwise, steps in a process may be conducted
sequentially in the order as they are listed, with or without
overlapping with one or more other step, or in any other order, as
the case may be. In addition, one or more or even all steps may be
conducted simultaneously with regard to the same or different batch
of material. For example, in a continuous process, while a first
step in a process is being conducted with respect to a raw material
just fed into the beginning of the process, a second step may be
carried out simultaneously with respect to an intermediate material
resulting from treating the raw materials fed into the process at
an earlier time in the first step. Preferably, the steps are
conducted in the order described.
[0025] Unless otherwise indicated, all numbers indicating
quantities in the present disclosure are to be understood as being
modified by the term "about" in all instances. It should also be
understood that the specific numerical values used in the
specification and claims constitute specific embodiments. Efforts
have been made to ensure the accuracy of the data in the examples.
However, it should be understood that any measured data inherently
contain a certain level of error due to the limitation of the
technique and equipment used for making the measurement.
[0026] As used herein, the indefinite article "a" or "an" shall
mean "at least one" unless specified to the contrary or the context
clearly indicates otherwise. Thus, embodiments using "a
fractionation column" include embodiments where one, two or more
fractionation columns are used, unless specified to the contrary or
the context clearly indicates that only one fractionation column is
used. Likewise, "a C12+ component" should be interpreted to include
one, two or more C12+ components unless specified or indicated by
the context to mean only one specific C12+ component.
[0027] As used herein, "wt %" means percentage by weight, "vol %"
means percentage by volume, "mol %" means percentage by mole, "ppm"
means parts per million, and "ppm wt" and "wppm" are used
interchangeably to mean parts per million on a weight basis. All
"ppm" as used herein are ppm by weight unless specified otherwise.
All concentrations herein are expressed on the basis of the total
amount of the composition in question. All ranges expressed herein
should include both end points as two specific embodiments unless
specified or indicated to the contrary.
[0028] As used herein, the term "methylcyclopentanone" includes
both isomers 2-methylcyclopentanone (CAS Registry No. 1120-72-5)
and 3-methylcyclopentanone (CAS Registry No. 1757-42-2), at any
proportion between them, unless it is clearly specified to mean
only one of these two isomers or the context clearly indicates that
is the case. It should be noted that under the conditions of the
various steps of the present processes, the two isomers may undergo
isomerization reactions to result in a ratio between them different
from that in the raw materials immediately before being charged
into a vessel such as a fractionation column.
[0029] As used herein, the term "C12+ component" means compounds
having at least 12 carbon atoms. Examples of C12+ components
include, among others, cyclohexylbenzene, biphenyl, bicyclohexane,
methylcyclopentylbenzene, 1,2-biphenylbenzene, 1,3-biphenylbenzene,
1,4-biphenylbenzene, 1,2,3-triphenylbenzene,
1,2,4-triphenylbenzene, 1,3,5-triphenylbenzene, and corresponding
oxygenates such as alcohols, ketones, acids, and esters derived
from these compounds. As used herein, the term "C18+ component"
means compounds having at least 18 carbon atoms. Examples of C18+
components include, among others, diicyclohexylbenzenes ("DiCHB,"
including all isomers thereof, including 1,2-dicyclohexylbenzene,
1,3-dicyclohexylbenzene, 1,4-dicyclohexylbenzene, and mixtures of
two or more thereof at any proportion), tricyclohexylbenzenes
("TriCHB," including all isomers thereof, including
1,2,3-tricyclohexylbenzene, 1,2,4-tricyclohexylbenzene,
1,3,5-tricyclohexylbenzene, and mixtures of two or more thereof at
any proportion).
[0030] In the present disclosure, a location "in the vicinity of"
an end (top or bottom) of a column means a location within a
distance of a*Hc from the end (top or bottom) of the column, where
Hc is the height of the column from the bottom to the top, and
a1.ltoreq.a.ltoreq.a2, where a1 and a2 can be, independently, 0,
0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11,
0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, as long as
a1<a2. For example, a location in the vicinity of an end (top or
bottom) of a column can have an absolute distance from the end of
at most D meters, where D can be 5.0, 4.5, 4.0, 3.5, 3.0, 2.5, 2.0,
1.5, 1.0, 0.8, 0.5, 0.4, 0.3, 0.2, 0.1, or 0.
[0031] As used herein, "oxygen" means molecular oxygen (O.sub.2)
unless the context clearly indicates or specifies otherwise.
[0032] Nomenclature of elements and groups thereof used herein are
pursuant to the Periodic Table used by the International Union of
Pure and Applied Chemistry after 1988. An example of the Periodic
Table is shown in the inner page of the front cover of Advanced
Inorganic Chemistry, 6.sup.th Edition, by F. Albert Cotton et al.
(John Wiley & Sons, Inc., 1999).
[0033] The process and device of the present disclosure can be used
for removing water and/or oxygen from any crude organic liquid. The
organic liquid may comprise one or more organic compound(s).
Non-limiting examples of compounds contained in such organic
liquids include: substituted and unsubstituted aliphatic
hydrocarbons such as cyclic and acyclic alkanes and alkenes;
substituted or unsubstituted aromatic hydrocarbons such as benzene,
biphenyl; alcohols; amines; ethers; ketones; aldehydes; carboxylic
acids; esters; and the like; and mixtures thereof. Preferably, one
or more of the organic compounds comprise from 3 to 20 carbon atoms
in its molecular structure. Preferably, one or more of the organic
compound(s) has a melting point in a range from mp1.degree. C. to
mp2.degree. C., where mp1 and mp2 can be, e.g., -50, -45, -40, -35,
-30, -25, -20, -15, -10, -5, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45,
50, 55, 60, as long as mp1<mp2. Preferably, one or more of the
organic compound(s) has a boiling point in a range from bp1.degree.
C. to bp2.degree. C., where bp1 and bp2 can be, e.g., 40, 45, 50,
55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, as
long as bp1<bp2. Preferably, the crude organic liquid comprises
one or more of the following: benzene, toluene, o-xylene, m-xylene,
p-xylene, ethylbenzene, cumene, cyclopentane, cyclohexane,
cyclohexene, cyclohexanol, cyclohexanone, and phenol. Preferably,
the crude organic liquid comprises a primary organic compound at a
concentration higher than Cpc wt % based on the total weight of the
crude organic liquid, where Cpc can be, e.g., 70, 75, 80, 85, 90,
91, 92, 93, 94, 95, 96, 97, 98, 99.0, 99.1, 99.2, 99.3, 99.4, 99.5,
99.6, 99.7, 99.8, or even 99.9.
[0034] A particularly preferred crude organic liquid comprises
benzene, such as a benzene stream comprising at least 95 wt % of
benzene based on the total weight of the stream. Benzene is used a
feed in processes for making other basic industrial chemicals such
as ethylbenzene, cumene, cyclohexylbenzene, cyclohexane,
cyclohexanol, cyclohexanone, phenol, caprolactam, and the like. It
is highly desired that such benzene feed comprises water and/or
molecular oxygen at a low concentration.
[0035] Water and oxygen can be present in the crude organic liquid
stream due to method used for making the crude organic liquid
stream, exposure to ambient air during transportation, storage, and
the like. Under extreme conditions, after prolonged exposure to the
ambient condition, the crude organic liquid stream may become even
saturated with water and/or molecular oxygen.
[0036] The organic liquid stream subjected to purification in the
present disclosure may contain water at a concentration of Cw1 ppm
and molecular oxygen at a concentration of Cox1 ppm based on the
total weight of the crude organic liquid stream, where:
[0037] Cw1(min).ltoreq.Cw1.ltoreq.Cw1(max), where Cw1(min) and
Cw1(max) can be, independently, 10, 20, 30, 40, 50, 60, 70, 80, 90,
100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, as long as
Cw1(min)<Cw1(max); and
[0038] Cox1(min).ltoreq.Cox1.ltoreq.Cox1(max), where Cox1(min) and
Cox1(max) can be, independently, 10, 20, 30, 40, 50, 60, 70, 80,
90, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000,
4000, 5000, 6000, 7000, 8000, 9000, 10000, as long as
Cox1(min)<Cox1(max).
[0039] The crude organic liquid stream fed to the distillation
column according to the present disclosure may have a temperature
of T1.degree. C. in a range from T1(min) .degree. C. to T1(max)
.degree. C., where T1(min) and T1(max) can be, independently, -20,
-15, -10, -5, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35,
40, 45, 50, 55, 60, as long as T1(min)<T1(max), and T1 is higher
than the melting point of the crude liquid stream. In the case
where the crude organic liquid comprises primarily benzene, it is
desired that 8.ltoreq.T1.ltoreq.60. Preferably, the temperature in
the vicinity of the top of the distillation column is in the
vicinity of ambient temperature. Preferably, the temperature of the
crude organic liquid stream fed into the distillation column and
the temperature in the vicinity of the top of the distillation
column are both in the vicinity of ambient temperature.
[0040] Upon treatment using the method and/or device of the present
disclosure, the purified organic liquid stream may comprise water
at a concentration of Cw2 ppm and molecular oxygen at a
concentration of Cox2 ppm, based on the total weight of the
purified organic liquid stream, where:
[0041] Cw2(min).ltoreq.Cw2.ltoreq.Cw2(max), where Cw2(min) and
Cw2(max) can be, independently, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7,
0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70,
80, 90, 100, as long as Cw2(min)<Cw2(max); and
[0042] Cox2(min).ltoreq.Cox2.ltoreq.Cox2(max), where Cox2(min) and
Cox2(max) can be, independently, 0.01, 0.02, 0.03, 0.04, 0.05,
0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8,
0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, as long as
Cox2(min)<Cox2(max).
[0043] The purified organic liquid stream contains water and/oxygen
at a concentration significantly lower than the crude organic
liquid stream. Preferably the following is achieved:
[0044] R1.ltoreq.Cw1/Cw2.ltoreq.R2, where Cw1 and Cw2 are defined
above, R1 and R2 can be, independently, 2, 3, 4, 5, 6, 7, 8, 9, 10,
20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700,
800, 900, and 1000, as long as R1<R2; and
[0045] R3.ltoreq.Cox1/Cox2.ltoreq.R4, where Cox1 and Cox2 are
defined above, R3 and R4 can be, independently, 2, 3, 4, 5, 6, 7,
8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500,
600, 700, 800, 900, and 1000, as long as R3<R4.
[0046] The purified organic liquid stream exiting the distillation
column may have a temperature of T2.degree. C. in a range from
T2(min) .degree. C. to T2(max) .degree. C., where T2(min) and
T2(max) can be, independently, 20, 25, 30, 35, 40, 45, 50, 55, 60,
65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, as long as
T2(min)<T2(max), and T2 is higher than the melting point of the
crude liquid and lower than the boiling point of the purified
organic liquid. In the case where the crude organic liquid
comprises primarily benzene, it is desired that
20.ltoreq.T2.ltoreq.75.
[0047] The side effluent stream, due to the temperature gradient
present in the distillation column, has a water concentration of
Cw3 wt %, based on the total weight of the side effluent stream,
where Cw3(min).ltoreq.Cw3.ltoreq.Cw3(max), Cw3(min) and Cw3(max)
can be, independently, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07,
0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3,
4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, as
long as Cw3(min)<Cw3(max), and Cw2<Cw3<Cw1, where Cw1 and
Cw2 are defined above. The side effluent stream may comprise one,
two, or more phases. For example, the side effluent stream may be a
mixture comprising an aqueous phase and an organic phase. The
distillation column can be designed such that the capacity of the
column in the vicinity of the third location is sufficiently high
to allow substantial separation of an aqueous phase and an organic
phase inside the distillation column resulting in the side effluent
stream drawn from the distillation column comprising water at a
high concentration.
[0048] The side effluent stream has a temperature of T3.degree. C.,
which is higher than the temperature in the vicinity of the top of
the distillation column. Preferably,
T3(min).ltoreq.T3.ltoreq.T3(max), where T3(min) and T3(max) can be,
independently, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24,
25, 26, 28, 30, 32, 34, 35, 36, 38, 40, 42, 44, 45, 46, 48, 50, 52,
54, 55, 56, 58, 60, as long as T3(min)<T3(max).
[0049] Preferably, the side effluent stream is delivered into a
settling vessel, where the organic phase and the aqueous phase are
allowed to settle and separate. If the organic phase has a density
lower than the aqueous phase, as in the case where the organic
phase consists essentially of benzene and the aqueous phase
consists essentially of water, the organic phase will be the upper
phase in the drum. At least a portion of the separate organic phase
can be recycled to the distillation column by, e.g., using a pump,
at a seventh location on the shell. The seventh location is
preferably between the first location and the third location. The
aqueous phase, preferably comprising water at a concentration
higher than 95%, can be delivered to a waste water treatment
facility where organic materials contained therein can be further
removed or destroyed.
[0050] At a location in the vicinity of the bottom of the
distillation column, heat is provided to the fluid inside the
distillation column by, e.g., a heat exchanger, which can be
located at least partly inside or outside the shell of the
distillation column Preferably, the heat input vaporizes at least a
portion of the liquid inside the distillation column. The vapor
travels upwards, cools down gradually and extracts water from
liquid flowing downwards along the way. Thus, preferably, the
temperature of the heat exchange medium (such as steam) used in the
heat exchanger is higher than the boiling point of the organic
material which constitutes a great majority of the fluid at the
location of heat input.
[0051] Preferably, the amount of heat input at the seventh location
is controlled by temperature measured at the third location. Thus,
if the measured temperature at the third location is lower than the
target temperature, more heat can be provided at the seventh
location, and vice versa, by using an automatic feedback loop.
[0052] From a location in the vicinity of the top of the
distillation column, a gas effluent stream comprising nitrogen,
oxygen, trace water and organic materials is drawn. Because the
temperature in the vicinity of the top of the distillation column
is quite low, e.g., around ambient temperature, concentration of
organic materials in the gas effluent stream is desirably low.
Nonetheless, the gas effluent stream can be combined with other
fuel gas stream and then delivered to a furnace, where the organic
material(s) is burned to provide heat needed for the distillation
column or other devices on the site.
[0053] The distillation column may preferably has a total number of
theoretical trays of N(1) from the top to the bottom, where
N(1)(min).ltoreq.N(1).ltoreq.N(1)(max), where N(1)(min) and
N(1)(max) can be, independently, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, as long as N(1)(min)<N(1)(max).
Preferably, the third location and the fourth location are chosen
such that the number of theoretical trays from the third location
to the fourth location is N(2), and R5.ltoreq.N(2)/N(1).ltoreq.R6,
where N(1) is defined above, R5 and R6 can be, independently, 1/12,
1/6, 1/4, 1/3, 5/12, 1/2, 7/12, 2/3, as long as R5<R6.
Preferably, N(2)(min).ltoreq.N(2).ltoreq.N(2)(max), where N(2)(min)
and N(2)(max) can be, independently, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5,
2.6, 2.7, 2.8, 2.9, 3.0, 3.2, 3.4, 3.5, 3.6, 3.8, 4.0, 4.2, 4.4,
4.5, 4.6, 4.8, 5.0, as long as N(2)(min)<N(2)(max).
[0054] The pressure inside the distillation column is preferably
close to or the same as the ambient pressure. Thus, preferably, the
absolute pressure inside the distillation column at the fourth
location is from Pam-50 kPa to Pam+50 kPa, where Pam is ambient
pressure.
[0055] Crude benzene purified according to the present disclosure
can be advantageously used for making cumene and cyclohexylbenzene,
which, in turn, can be used for making phenol, acetone or
cyclohexanone. Because the catalysts used making cumene and
cyclohexylbenzene are sensitive to the presence of water and/or
oxygen in the benzene feed, using a benzene feed purified according
to the present invention is particularly beneficial.
[0056] The following is a description of the process for making
phenol and/or cyclohexanone starting from hydroalkylation of
benzene treated by using the present invention to make
cyclohexylbenzene.
Supply of Cyclohexylbenzene
[0057] The cyclohexylbenzene can be produced and/or recycled as
part of an integrated process for producing phenol and
cyclohexanone from benzene. In such an integrated process, benzene
is initially converted to cyclohexylbenzene by any conventional
technique, including oxidative coupling of benzene to make biphenyl
followed by hydrogenation of the biphenyl. However, in practice,
the cyclohexylbenzene is desirably produced by contacting benzene
with hydrogen under hydroalkylation conditions in the presence of a
hydroalkylation catalyst whereby benzene undergoes the following
Reaction-1 to produce cyclohexylbenzene (CHB):
##STR00001##
[0058] Alternatively, cyclohexylbenzene can be produced by direct
alkylation of benzene with cyclohexene in the presence of a
solid-acid catalyst such as molecular sieves in the MCM-22 family
according to the following Reaction-2:
##STR00002##
[0059] U.S. Pat. Nos. 6,730,625 and 7,579,511, WO2009/131769, and
WO2009/128984 disclose processes for producing cyclohexylbenzene by
reacting benzene with hydrogen in the presence of a hydroalkylation
catalyst, the contents of all of which are incorporated herein by
reference in their entirety.
[0060] The catalyst employed in the hydroalkylation reaction is a
bifunctional catalyst comprising a molecular sieve, such as one of
the MCM-22 type described above and a hydrogenation metal.
[0061] Any known hydrogenation metal may be employed in the
hydroalkylation catalyst, specific, non-limiting, suitable examples
of which include Pd, Pt, Rh, Ru, Ir, Ni, Zn, Sn, Co, with Pd being
particularly advantageous. Desirably, the amount of hydrogenation
metal present in the catalyst is from 0.05 wt % to 10.0 wt %, such
as from 0.10 wt % and 5.0 wt %, of the total weight of the
catalyst.
[0062] In addition to the molecular sieve and the hydrogenation
metal, the hydroalkylation catalyst may comprise one or more
optional inorganic oxide support materials and/or binders. Suitable
inorganic oxide support material(s) include, but are not limited
to, clay, non-metal oxides, and/or metal oxides. Specific,
non-limiting examples of such support materials include: SiO.sub.2,
Al.sub.2O.sub.3, ZrO.sub.2, Y.sub.2O.sub.3, Gd.sub.2O.sub.3, SnO,
SnO.sub.2, and mixtures, combinations and complexes thereof.
[0063] The effluent from the hydroalkylation reaction
(hydroalkylation reaction product mixture) or from the alkylation
reaction (alkylation reaction product mixture) may contain some
polyalkylated benzenes, such as dicyclohexylbenzenes (DiCHB),
tricyclohexylbenzenes (TriCHB), methylcyclopentylbenzene, unreacted
benzene, cyclohexane, bicyclohexane, biphenyl, and other
contaminants. Thus, typically, after the reaction, the
hydroalkylation reaction product mixture is separated by
distillation to obtain a C6 fraction containing benzene,
cyclohexane, a C12 fraction containing cyclohexylbenzene and
methylcyclopentylbenzene, and a heavies fraction containing, e.g.,
C18s such as DiCHBs and C24s such as TriCHBs. The unreacted benzene
may be recovered by distillation and recycled to the
hydroalkylation or alkylation reactor. The cyclohexane may be sent
to a dehydrogenation reactor, with or without some of the residual
benzene, and with or without co-fed hydrogen, where it is converted
to benzene and hydrogen, which can be recycled to the
hydroalkylation/alkylation step.
[0064] Depending on the quantity of the heavies fraction, it may be
desirable to either (a) transalkylate the C18s such as DiCHB and
C24s such as TriCHB with additional benzene or (b) dealkylate the
C18s and C24s to maximize the production of the desired
monoalkylated species.
[0065] Transalkylation with additional benzene is desirably
effected in a transalkylation reactor, which is separate from the
hydroalkylation reactor, over a suitable transalkylation catalyst,
such as a molecular sieve of the MCM-22 type, zeolite beta, MCM-68
(see U.S. Pat. No. 6,049,018), zeolite Y, zeolite USY, and
mordenite. The transalkylation reaction is desirably conducted
under at least partially liquid phase conditions, which suitably
include a temperature in the range from 100.degree. C. to
300.degree. C., a pressure in the range from 800 kPa to 3500 kPa, a
weight hourly space velocity from 1 hr.sup.-1 to 10 hr.sup.-1 on
total feed, and a benzene/dicyclohexylbenzene weight ratio in a
range from 1:1 to 5:1.
[0066] Dealkylation is also desirably effected in a reactor
separate from the hydroalkylation reactor, such as a reactive
distillation unit, at a temperature of about 150.degree. C. to
about 500.degree. C. and a pressure in a range from 15 to 500 psig
(200 to 3550 kPa) over an acid catalyst such as an aluminosilicate,
an aluminophosphate, a silicoaluminophosphate, amorphous
silica-alumina, an acidic clay, a mixed metal oxide, such as
WO.sub.x/ZrO.sub.2, phosphoric acid, sulfated zirconia and mixtures
thereof. Desirably, the acid catalyst includes at least one
aluminosilicate, aluminophosphate or silicoaluminophosphate of the
FAU, AEL, AFI and MWW family. Unlike transalkylation, dealkylation
can be conducted in the absence of added benzene, although it may
be desirable to add benzene to the dealkylation reaction to reduce
coke formation. In this case, the weight ratio of benzene to
poly-alkylated aromatic compounds in the feed to the dealkylation
reaction can be from 0 to about 0.9, such as from about 0.01 to
about 0.5. Similarly, although the dealkylation reaction can be
conducted in the absence of added hydrogen, hydrogen is desirably
introduced into the dealkylation reactor to assist in coke
reduction. Suitable hydrogen addition rates are such that the molar
ratio of hydrogen to poly-alkylated aromatic compound in the total
feed to the dealkylation reactor can be from about 0.01 to about
10.
[0067] The transalkylation or dealkylation product mixture
comprising benzene, C12s and heavies can then be separated to
obtain a C6 fraction, which comprises primarily benzene and can be
recycled to the hydroalkylation/alkylation step, a C12s fraction
comprising primarily cyclohexylbenzene, and a heavies fraction
which can be subjected to a transalkylation/dealkylation reaction
again or discarded.
[0068] The cyclohexylbenzene freshly produced and/or recycled may
be purified before being fed to the oxidation step to remove at
least a portion of, among others, methylcyclopentylbenzene,
olefins, phenol, acid, and the like. Such purification may include,
e.g., distillation, hydrogenation, caustic wash, and the like.
[0069] The cyclohexylbenzene feed to the oxidizing step may
contain, based on the total weight of the feed, one or more of the
following: (i) bicyclohexane at a concentration in a range from at
1 ppm to 1 wt %, such as from 10 ppm to 8000 ppm; (ii) biphenyl at
a concentration in a range from 1 ppm to 1 wt %, such as from 10
ppm to 8000 ppm; (iii) water at a concentration up to 5000 ppm,
such as from 100 ppm to 1000 ppm; and (iv) olefins or alkene
benzenes, such as phenylcyclohexene, at a concentration no greater
than 1000 ppm.
Oxidation of Cyclohexylbenzene
[0070] In the oxidation step, at least a portion of the
cyclohexylbenzene contained in the oxidation feed is converted to
cyclohexyl-1-phenyl-1-hydroperoxide, the desired hydroperoxide,
according to the following Reaction-3:
##STR00003##
[0071] In exemplary processes, the oxidizing step may be
accomplished by contacting an oxygen-containing gas, such as air
and various derivatives of air, with the feed comprising
cyclohexylbenzene. For example, a stream of pure O.sub.2, O.sub.2
diluted by inert gas such as nitrogen, pure air, or other
O.sub.2-containing mixtures can be pumped through the
cyclohexylbenzene-containing feed in an oxidation reactor.
[0072] The oxidation may be conducted in the absence or presence of
a catalyst. Examples of suitable oxidation catalysts include those
having a structure of formula (FC-I), (FC-II), or (FC-III)
below:
##STR00004##
[0073] where:
[0074] A represents a ring optionally comprising a nitrogen,
sulfur, or oxygen in the ring structure, and optionally substituted
by an alkyl, an alkenyl, a halogen, or a N-, S-, or O-containing
group or other group;
[0075] X represents a hydrogen, an oxygen free radical, a hydroxyl
group, or a halogen;
[0076] R.sup.1, the same or different at each occurrence,
independently represents a halogen, a N-, S-, or O-containing
group, or a linear or branched acyclic alkyl or cyclic alkyl group
having 1 to 20 carbon atoms, optionally substituted by an alkyl, an
alkenyl, a halogen, or a N-, S-, or O-containing group or other
group; and
[0077] m is 0, 1 or 2.
[0078] Examples of particularly suitable catalysts for the
oxidation step include those represented by the following formula
(FC-IV):
##STR00005##
[0079] where:
[0080] R.sup.2, the same or different at each occurrence,
independently represents a halogen, a N-, S-, or O-containing
group, or an optionally substituted linear or branched acyclic
alkyl or cyclic alkyl group having 1 to 20 carbon atoms; and
[0081] n is 0, 1, 2, 3, or 4.
[0082] One especially suitable catalyst having the above formula
(FC-IV) for the oxidation step is NHPI (N-hydroxyphthalimide). For
example, the feed to the oxidizing step can comprise from 10 to
2500 ppm of NHPI by weight of the cyclohexylbenzene in the
feed.
[0083] Other non-limiting examples of the oxidation catalyst
include: 4-amino-N-hydroxyphthalimide,
3-amino-N-hydroxyphthalimide, tetrabromo-N-hydroxyphthalimide,
tetrachloro-N-hydroxyphthalimide, N-hydroxyhetimide,
N-hydroxyhimimide, N-hydroxytrimellitimide,
N-hydroxybenzene-1,2,4-tricarboximide, N,N'-dihydroxy(pyromellitic
diimide), N,N'-dihydroxy(benzophenone-3,3',4,4'-tetracarboxylic
diimide), N-hydroxymaleimide, pyridine-2,3-dicarboximide,
N-hydroxysuccinimide, N-hydroxy(tartaric imide),
N-hydroxy-5-norbornene-2,3-dicarboximide,
exo-N-hydroxy-7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboximide,
N-hydroxy-cis-cyclohexane-1,2-dicarboximide,
N-hydroxy-cis-4-cyclohexene-1,2 dicarboximide,
N-hydroxynaphthalimide sodium salt,
N-hydroxy-o-benzenedisulphonimide, and
N,N',N''-trihydroxyisocyanuric acid.
[0084] These oxidation catalysts can be used either alone or in
conjunction with a free radical initiator, and further can be used
as liquid-phase, homogeneous catalysts or can be supported on a
solid carrier to provide a heterogeneous catalyst. Desirably, the
N-hydroxy substituted cyclic imide or the
N,N',N''-trihydroxyisocyanuric acid is employed in an amount from
0.0001 wt % to 15 wt %, such as from 0.001 wt % to 5 wt %, of the
cyclohexylbenzene feed.
[0085] Non-limiting examples of suitable reaction conditions of the
oxidizing step include a temperature in a range from 70.degree. C.
to 200.degree. C., such as 90.degree. C. to 130.degree. C., and a
pressure in a range from 50 kPa to 10,000 kPa. A basic buffering
agent may be added to react with acidic by-products that may form
during the oxidation. In addition, an aqueous phase may be
introduced into the oxidation reactor. The reaction may take place
in a batch or continuous flow fashion.
[0086] The reactor used for the oxidizing step may be any type of
reactor that allows for the oxidation of cyclohexylbenzene by an
oxidizing agent, such as molecular oxygen. A particularly
advantageous example of the suitable oxidation reactor is a bubble
column reactor capable of containing a volume of the reaction media
and bubbling an O.sub.2-containing gas stream (such as air) through
the media. For example, the oxidation reactor may comprise a
simple, largely open vessel with a distributor inlet for the
oxygen-containing gas stream. The oxidation reactor may have means
to withdraw a portion of the reaction media and pump it through a
suitable cooling device and return the cooled portion to the
reactor, thereby managing the heat generated in the reaction.
Alternatively, cooling coils providing indirect cooling, e.g., by
cooling water, may be operated within the oxidation reactor to
remove at least a portion of the generated heat. Alternatively, the
oxidation reactor may comprise a plurality of reactors in series
and/or in parallel, each operating at the same or different
conditions selected to enhance the oxidation reaction in the
reaction media with different compositions. The oxidation reactor
may be operated in a batch, semi-batch, or continuous flow manner
well known to those skilled in the art.
Composition of the Oxidation Reaction Product Mixture
[0087] Desirably, the oxidation reaction product mixture exiting
the oxidation reactor contains cyclohexyl-1-phenyl-1-hydroperoxide
at a concentration in a range from Chp1 wt % to Chp2 wt %, based on
the total weight of the oxidation reaction product mixture, where
Chp1 and Chp2 can be, independently, 5, 10, 15, 20, 25, 30, 35, 40,
45, 50, 55, 60, 65, 70, 75, 80, as long as Chp1<Chp2.
Preferably, the concentration of
cyclohexyl-1-phenyl-1-hydroperoxide in the oxidation reaction
product mixture is at least 20% by weight of the oxidation reaction
product mixture. The oxidation reaction product mixture may further
comprise residual cyclohexylbenzene at a concentration in a range
from Cchb1 wt % to Cchb2 wt %, based on the total weight of the
oxidation reaction product mixture, where Cchb1 and Cchb2 can be,
independently, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80,
85, 90, 95, as long as Cchb1<Cchb2. Preferably, the
concentration of cyclohexylbenzene in the oxidation reaction
product mixture is at most 65% by weight of the oxidation reaction
product mixture.
[0088] In addition, the oxidation reaction product mixture may
contain one or more hydroperoxides other than
cyclohexyl-1-phenyl-1-hydroperoxide generated as byproduct(s) of
the oxidation reaction of cyclohexylbenzene, or as the oxidation
reaction product of oxidizable component(s) other than
cyclohexylbenzene that may have been contained in the feed supplied
to the oxidizing step, such as cyclohexyl-2-phenyl-1-hydroperoxide,
cyclohexyl-3-phenyl-1-hydroperoxide, and methylcyclopentylbenzene
hydroperoxides. These undesired hydroperoxides are present at a
total concentration from Cu1 wt % to Cu2 wt %, where Cu1 and Cu2
can be, independently, 0.1, 0.2, 0.3, 0.5, 0.7, 0.9, 1.0, 1.2, 1.4,
1.5, 1.6, 1.8, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 6.0, 7.0, 8.0, as
long as Cu1<Cu2. They are undesirable because they may not
convert into phenol and cyclohexanone in the cleavage reaction at
the desired conversion and/or selectivity, resulting in overall
yield loss.
[0089] As noted above, the oxidation reaction product mixture may
also contain phenol as a further by-product of the oxidation
reaction. The concentration of phenol (CPh) in the oxidation
reaction product mixture exiting the oxidation reactor(s) can range
from CPh1 ppm to CPh2 ppm, where CPh1 and CPh2 can be,
independently: 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350,
400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000,
1500, 2000, as long as CPh1<CPh2.
[0090] The oxidation reaction product mixture may contain water.
The concentration of water in the oxidation reaction product
mixture exiting the oxidation reactor may range from C1a ppm to C1b
ppm, based on the total weight of the oxidation reaction product
mixture, where C1a and C1b can be, independently: 30, 40, 50, 60,
70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600,
650, 700, 750, 800, 850, 900, 950, 1000, 1500, 2000, 2500, 3000,
3500, 4000, 4500, or 5000, as long as C1a<C1b.
[0091] The oxidation reaction product mixture may also contain part
or all of any catalyst, such as NHPI, supplied to the oxidizing
step. For example, the oxidation reaction product mixture may
contain from 10 to 2500 ppm of NHPI, such as from 100 to 1500 ppm
by weight of NHPI.
Treatment of the Oxidation Reaction Product Mixture
[0092] In the process of the present disclosure, before being
supplied to the cleavage step, at least a portion of the oxidation
reaction product mixture may be separated. The separation process
may include subjecting at least a portion of the oxidation reaction
product mixture to vacuum evaporation so as to recover: (i) a first
fraction comprising the majority of the
cyclohexyl-1-phenyl-1-hydroperoxide and other higher boiling
components of the oxidation reaction product mixture portion, such
as other hydroperoxides and NHPI catalyst, if present in the
oxidation reaction product mixture portion; and (ii) a second
fraction comprising a major portion of the cyclohexylbenzene,
phenol, if any, and other lower boiling components of the oxidation
reaction product mixture portion.
[0093] Desirably, in the first fraction, the concentration of
cyclohexyl-1-phenyl-1-hydroperoxide can range from Cc1 wt % to Cc2
wt %, and the concentration of cyclohexylbenzene can range from Cd1
wt % to Cd2 wt %, based on the total weight of the first fraction,
where Cc1 and Cc2 can be, independently, 40, 45, 50, 55, 60, 65,
70, 75, 80, 85, 90, as long as Cc1<Cc2; and Cd1 and Cd2 can be,
independently, 10, 15, 20, 25, 30, 35, 40, 45, 50, as long as
Cd1<Cd2.
[0094] Advantageously, in the second fraction, the concentration of
cyclohexyl-1-phenyl-1-hydroperoxide can range from Cc3 wt % to Cc4
wt %, and the concentration of cyclohexylbenzene can range from Cd3
wt % to Cd4 wt %, based on the total weight of the second fraction,
where Cc3 and Cc4 can be, independently, 0.01, 0.05, 0.10, 0.20,
0.40, 0.50, 0.60, 0.80, 1.00, 1.50, 2.00, 2.50, 3.00, 3.50, 4.00,
4.50, 5.00, as long as Cc3<Cc4; and Cd3 and Cd4 can be,
independently, 90, 92, 94, 95, 96, 97, 98, or even 99, as long as
Cd3<Cd4.
[0095] Because cyclohexylbenzene hydroperoxide is prone to
decomposition at elevated temperatures, e.g., at above 150.degree.
C., the vacuum evaporation step to separate the oxidation reaction
product mixture into the first and second fractions is conducted at
a relatively low temperature, e.g., no higher than 130.degree. C.,
or no higher than 120.degree. C., or even no higher than
110.degree. C. Cyclohexylbenzene has a high boiling point
(239.degree. C. at 101 kPa). Thus, at acceptable
cyclohexylbenzene-removal temperatures, cyclohexylbenzene tends to
have very low vapor pressure. Accordingly, preferably, to
effectively remove a meaningful amount of cyclohexylbenzene from
the oxidation reaction product mixture, the oxidation reaction
product mixture is subjected to a very low absolute pressure, e.g.,
in a range from Pc1 kPa to Pc2 kPa, where Pc1 and Pc2 can be,
independently, 0.05, 0.10, 0.15, 0.20, 0.25, 0.26, 0.30, 0.35,
0.40, 0.45, 0.50, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95,
1.00, 1.50, 2.00, 2.50, 3.00, as long as Pc1<Pc2. Particularly
advantageously, Pc1=0.25, and Pc2=1.5.
[0096] After separation of the oxidation reaction product mixture
into the first and second fractions, part or all of the first
fraction can be routed directly to the cleavage step. All or a
portion of the first fraction may be cooled before passage to the
cleavage step so as to cause crystallization of the unreacted imide
oxidation catalyst. The imide crystals may then be recovered for
reuse either by filtration or by scraping from a heat exchanger
surface used to effect the crystallization.
[0097] The second fraction produced from the oxidation reaction
product mixture may be treated to reduce the level of phenol
therein before part or all of the cyclohexylbenzene in the second
fraction is recycled to the hydrogenation.
[0098] Treatment of the second fraction can comprise contacting at
least a portion of the second fraction with an aqueous composition
comprising a base under conditions such that the base reacts with
the phenol to produce a phenoate species which remains in the
aqueous composition. A strong base, that is a base having a
pK.sub.b value less than 3, such as less than 2, 1, 0, or -1, is
desirably employed in the treatment of the second fraction.
Particularly suitable bases include hydroxides of alkali metals
(e.g., LiOH, NaOH, KOH, RbOH), hydroxides of alkaline earth metals
(Mg(OH).sub.2, Ca(OH).sub.2, Sr(OH).sub.2, Ba(OH).sub.2), and
mixtures of one or more thereof. Phenol can react with these
hydroxides to form phenoates, which typically have higher
solubility in water than phenol per se. A particularly desirable
base is NaOH, which is cost efficient and capable of reacting with
phenol in the second fraction to produce sodium phenoate. It should
be noted that, when a hydroxide is used as the base, because of the
reaction of CO.sub.2 present in the atmosphere with the hydroxide,
the aqueous composition may comprise, at various concentrations,
one or more of a corresponding carbonate, bicarbonate, or
carbonate-hydroxide complex. Desirably, the aqueous composition
comprising the base has a pH of at least 8, preferably at least
10.
[0099] Contacting of the second fraction with the aqueous
composition comprising a base produces an aqueous phase containing
at least part of the phenol and/or a derivative thereof from the
second fraction and an organic phase containing cyclohexylbenzene
and having a reduced concentration of phenol as compared with the
second fraction. Desirably, the phenol concentration in the organic
phase is in the range from CPh7 ppm to CPh8 ppm, based on the total
weight of the organic phase, where CPh7 and CPh8 can be,
independently: 0, 10, 20, 30, 40, 50, 100, 150, 200, 250, as long
as CPh7<CPh8.
[0100] The organic phase can then be separated from the aqueous
phase, for example, spontaneously under gravity, and can then be
recycled to the oxidizing step as a third fraction either directly,
or more preferably, after water washing to remove base entrained in
the organic phase.
Cleavage Reaction
[0101] In the cleavage reaction, at least a portion of the
cyclohexyl-1-phenyl-1-hydroperoxide decomposes in the presence of
an acid catalyst in high selectivity to cyclohexanone and phenol
according to the following desired Reaction-4:
##STR00006##
The cleavage product mixture may comprise the acid catalyst,
phenol, cyclohexanone, cyclohexylbenzene, and contaminants.
[0102] The acid catalyst can be at least partially soluble in the
cleavage reaction mixture, is stable at a temperature of at least
185.degree. C. and has a lower volatility (higher normal boiling
point) than cyclohexylbenzene.
[0103] Acid catalysts preferably include, but are not limited to,
Bronsted acids, Lewis acids, sulfonic acids, perchloric acid,
phosphoric acid, hydrochloric acid, p-toluene sulfonic acid,
aluminum chloride, oleum, sulfur trioxide, ferric chloride, boron
trifluoride, sulfur dioxide, and sulfur trioxide. Sulfuric acid is
a preferred acid catalyst.
[0104] The cleavage reaction preferably occurs under cleavage
conditions including a temperature in a range from 20.degree. C. to
200.degree. C., or from 40.degree. C. to 120.degree. C., and a
pressure in a range from 1 to 370 psig (at least 7 kPa, gauge and
no greater than 2,550 kPa, gauge), or from 14.5 psig to 145 psig
(from 100 kPa, gauge to 1,000 kPa, gauge) such that the cleavage
reaction mixture is completely or predominantly in the liquid phase
during the cleavage reaction.
[0105] The cleavage reaction mixture can contain the acid catalyst
at a concentration in a range from Cad1 ppm to Cac2 ppm by weight
of the total weight of the cleavage reaction mixture, where Cad1
and Cac2 can be, independently, 10, 20, 30, 40, 50, 60, 80, 100,
150, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, 1000,
1500, 2000, 2500, 3000, 3500, 4000, 4500, or even 5000, as long as
Cad1<Cac2. Preferably, Cad1 is 50, and Cac2 is 200.
[0106] Conversion of hydroperoxides, such as
cyclohexyl-1-phenyl-1-hydroperoxide, and conveniently all
cyclohexyl-1-phenyl-1-hydroperoxide and other hydroperoxides, may
be very high in the cleavage reaction, e.g., at least AA wt %,
where AA can be 90.0, 91.0, 92.0, 93.0, 94.0, 95.0, 96.0, 97.0,
98.0, 99.0, 99.5, 99.9, or even 100, the percentage based on the
weight of a given hydroperoxide, or of all hydroperoxides fed to
the cleavage step. This is desirable because any hydroperoxide,
even the cyclohexyl-1-phenyl-1-hydroperoxide, becomes a contaminant
in the downstream processes.
[0107] Desirably, each mole of cyclohexyl-1-phenyl-1-hydroperoxide
produces one mole of phenol and one mole of cyclohexanone. However,
due to side reactions, the selectivity of the cleavage reaction to
phenol can range from Sph1% to Sph2% and the selectivity to
cyclohexanone can range from Sch1% to Sch2%, where Sph1, Sph2,
Sch1, and Sch2 can be, independently, 85, 87, 88, 89, 90, 91, 92,
93, 94, 95, 96, 97, 98, 99, or even 99.5, as long as Sph1<Sph2,
and Sch1<Sch2.
[0108] Besides the cleavage feed comprising cyclohexylbenzene
hydroperoxide, cyclohexylbenzene and other components originating
directly from the oxidation reaction product mixture, the cleavage
reaction mixture may further comprise other added materials, such
as the cleavage catalyst, a solvent, and one or more products of
the cleavage reaction such as phenol and cyclohexanone recycled
from the cleavage product mixture, or from a downstream separation
step. Thus, the cleavage reaction mixture inside the cleavage
reactor may comprise, based on the total weight of the cleavage
reaction mixture: (i) phenol at a concentration from CPh9 wt % to
CPh10 wt %, where CPh9 and CPh10 can be, independently, 20, 25, 30,
35, 40, 45, 50, 55, 60, 65, 70, 75, or 80, as long as
CPh9<CPh10; (ii) cyclohexanone at a concentration from Cch1 wt %
to Cch2 wt %, where Cch1 and Cch2 can be, independently, 20, 25,
30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80, as long as
Cch1<Cch2; and (iii) cyclohexylbenzene at a concentration from
Cchb7 wt % to Cchb8 wt %, where Cchb7 and Cchb8 can be,
independently, 5, 8, 9, 10, 12, 14, 15, 18, 20, 22, 24, 25, 26, 28,
30, 35, 40, 45, 50, 55, 60, 65, 70, as long as Cchb7<Cchb8.
[0109] The reactor used to effect the cleavage reaction (i.e., the
cleavage reactor) may be any type of reactor known to those skilled
in the art. For example, the cleavage reactor may be a simple,
largely open vessel operating in a near-continuous stirred tank
reactor mode, or a simple, open length of pipe operating in a
near-plug flow reactor mode. The cleavage reactor may comprise a
plurality of reactors in series, each performing a portion of the
conversion reaction, optionally operating in different modes and at
different conditions selected to enhance the cleavage reaction at
the pertinent conversion range. The cleavage reactor can be a
catalytic distillation unit.
[0110] The cleavage reactor can be operable to transport a portion
of the contents through a cooling device and return the cooled
portion to the cleavage reactor, thereby managing the exothermicity
of the cleavage reaction. Alternatively, the reactor may be
operated adiabatically. Cooling coils operating within the cleavage
reactor(s) can be used to at least a part of the heat
generated.
[0111] The cleavage product mixture exiting the cleavage reactor
may comprise, based on the total weight of the cleavage product
mixture: (i) phenol at a concentration from CPh11 wt % to CPh12 wt
%, where CPh11 and CPh12 can be, independently, 20, 25, 30, 35, 40,
45, 50, 55, 60, 65, 70, 75, or 80, as long as Ch11<CPh12; (ii)
cyclohexanone at a concentration from Cch3 wt % to Cch4 wt %, where
Cch3 and Cch4 can be, independently, 20, 25, 30, 35, 40, 45, 50,
55, 60, 65, 70, 75, or 80, as long as Cch3<Cch4; and (iii)
cyclohexylbenzene at a concentration from Cchb9 wt % to Cchb10 wt
%, where Cchb9 and Cchb10 can be, independently, 5, 8, 9, 10, 12,
14, 15, 18, 20, 22, 24, 25, 26, 28, 30, 35, 40, 45, 50, 55, 60, 65,
70, as long as Cchb9<Cchb10.
Separation and Purification
[0112] As discussed above, the cleavage product mixture may
comprise one or more contaminants. In embodiments disclosed herein,
the processes further comprise contacting at least a portion of a
contaminant with an acidic material to convert at least a portion
of the contaminant to a converted contaminant, thereby producing a
modified product mixture. Detailed description of the contaminant
treatment process can be found, e.g., in International Publication
WO2012/036822A1, the relevant content of which is incorporated
herein by reference in its entirety.
[0113] At least a portion of the cleavage product mixture may be
subjected to a neutralization reaction. Where a liquid acid such as
sulfuric acid is used as the cleavage catalyst, it is highly
desirable that the cleavage reaction product mixture is neutralized
by a base, such as an organic amine (e.g., methylamine, ethylamine,
diamines such as methylenediamine, propylene diamine, butylene
diamine, pentylene diamine, hexylene diamine, and the like) before
the mixture is subjected to separation to prevent equipment
corrosion by the acid. Desirably, the thus formed amine sulfate
salt has a boiling point higher than that of cyclohexylbenzene.
[0114] The neutralized cleavage reaction product mixture can then
be separated by methods such as distillation. In one example, in a
first distillation column after the cleavage reactor, a heavies
fraction comprising the amine salt is obtained at the bottom of the
column, a side fraction comprising cyclohexylbenzene is obtained in
the middle section, and an upper fraction comprising cyclohexanone,
phenol, methylcyclopentanone, and water is obtained.
[0115] The separated cyclohexylbenzene fraction can then be treated
and/or purified before being delivered to the oxidizing step. Since
the cyclohexylbenzene separated from the cleavage product mixture
may contain phenol and/or olefins such as cyclohexenylbenzenes, the
material may be subjected to treatment with an aqueous composition
comprising a base as described above for the second fraction of the
oxidation product mixture and/or a hydrogenation step as disclosed
in, for example, WO2011/100013A1, the entire contents of which are
incorporated herein by reference.
[0116] In one example, the fraction comprising phenol,
cyclohexanone, and water can be further separated by simple
distillation to obtain an upper fraction comprising primarily
cyclohexanone and methylcyclopentanone and a lower stream
comprising primarily phenol, and some cyclohexanone. Cyclohexanone
cannot be completely separated form phenol without using an
extractive solvent due to an azeotrope formed between these two.
Thus, the upper fraction can be further distillated in a separate
column to obtain a pure cyclohexanone product in the vicinity of
the bottom and an impurity fraction in the vicinity of the top
comprising primarily methylcyclopentanone, which can be further
purified, if needed, and then used as a useful industrial material.
The lower fraction can be further separated by a step of extractive
distillation using an extractive solvent (e.g., glycols such as
ethylene glycol, propylene glycol, diethylene glycol, triethylene
glycol, and the like) described in, e.g., co-assigned, co-pending
patent applications WO2013/165656A1 and WO2013/165659, the contents
of which are incorporated herein by reference in their entirety. An
upper fraction comprising cyclohexanone and a lower fraction
comprising phenol and the extractive solvent can be obtained. In a
subsequent distillation column, the lower fraction can then be
separated to obtain an upper fraction comprising a phenol product
and a lower fraction comprising the extractive solvent.
Uses of Cyclohexanone and Phenol
[0117] The cyclohexanone produced through the processes disclosed
herein may be used, for example, as an industrial solvent, as an
activator in oxidation reactions and in the production of adipic
acid, cyclohexanone resins, cyclohexanone oxime, caprolactam, and
nylons, such as nylon-6 and nylon-6,6.
[0118] The phenol produced through the processes disclosed herein
may be used, for example, to produce phenolic resins, bisphenol A,
.epsilon.-caprolactam, adipic acid, and/or plasticizers.
DESCRIPTION ACCORDING TO THE DRAWING
[0119] FIG. 1 schematically illustrates a crude organic liquid
purification process and device according to one example of the
present disclosure. The crude organic liquid can comprise, e.g.,
benzene, toluene, xylene, ethylbenzene, cumene, cyclohexane,
cyclohexene, cyclohexanol, cyclohexanone, and the like, containing
water and/or molecular oxygen.
[0120] In the device/process 101, a crude organic liquid feed
stream (e.g., benzene) 118 is supplied from a storage tank 117 into
a distillation column having a shell 103 at a first location 105 at
the side of the shell 103. Due to prolonged exposure to ambient
condition, the stream 118 may comprise water and/or molecular
oxygen at various concentrations up to saturation. Preferably, the
liquid stream 118 has a temperature from T1.degree. C. to
T2.degree. C., where T1 and T2 can be, independently, e.g., 5, 6,
7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 25, 30, 35, 40, 45, 50, 55,
60, as long as T1<T2. Preferably, the liquid stream 118 has a
temperature in the range Tam-X1.degree. C. to Tam+X2.degree. C.,
where Tam is the ambient temperature, and X1 and X2 can be,
independently, 30, 25, 24, 22, 20, 18, 16, 15, 14, 12, 10, 8, 6, 5,
4, 2, 1, 0, as long as X1 and X2 are not zero at the same time. A
structured packing or a series of trays or a combination of both
119 is housed inside the shell 103. The organic liquid fed into the
shell 103 flows downwards contacting the surface of the packing
and/or trays 119. A dry stream of nitrogen gas 122 supplied from
storage 121 is fed into the shell 103 at a second location 107 at
the side of the shell 103 below the first location. Preferably, the
nitrogen gas stream 122 has a water concentration of at most Cwn2
ppm by volume, and a molecular oxygen concentration of at most
Coxn2 ppm by volume, based on the total volume of the nitrogen,
where Cwn2 and Coxn2 can be, independently, e.g., 1000, 800, 600,
500, 400, 200, 100, 80, 60, 50, 40, 30, 20, 10, 8, 6, 5, 4, 2, 1.
The nitrogen gas travels upwards inside the shell as bubbles and/or
streams of gas while contacting the liquid flowing downwards. As a
result, water and/or molecular oxygen contained in the liquid are
at least partially displaced by nitrogen.
[0121] On the side of the shell 103, at a third location 113 below
the first location 105 and the second location 107, a side effluent
stream 113 is drawn. Stream 113 comprises water at a concentration
higher than in the crude organic liquid stream 118. In one example,
stream 113 preferably comprises a water phase and an organic phase,
and is subsequently delivered into a settling drum 135, where it
separates into a lower water phase 139, which can be discharged as
a waste water stream 141, and an upper organic phase 137, a stream
of which 142 can be at least recycled by a pump 143 as a recycle
stream 145 into the shell 103 at a location 115 on the side of the
shell 103. In another example, the distillation column is designed
such that sufficient separation of water and the organic phase
occurs inside the shell at the location 113, and thus, the side
effluent stream 133 comprises primarily water, which can be
discharged directly as a waste stream without the need of a
settling drum.
[0122] At a location 111 in the vicinity of the bottom of the shell
of the distillation column, heat is provided to the liquid inside
the shell 103 via a heat exchanger 131. The heat exchanger may be
located inside or outside of the shell 103. Preferably, the heat
input vaporizes a portion of the liquid inside the shell 103. The
heat provided establishes a descending temperature gradient along
the distillation column from the location 111 to the top. The
operation of the temperature gradient results in the liquid phase
at location 113 comprises water at a concentration higher than in
the stream 118. From the top of the shell 103, a vapor stream 147
comprising nitrogen, molecular oxygen and benzene exits.
Preferably, due to the low temperature at the top of the
distillation column, the concentration of organic materials in the
gas stream 147 is very low. This stream can be combined with other
organic waste stream and delivered to a combustion device to
provide the thermal energy needed for heat exchanger 131 or other
devices located on the same facility. Preferably, molecular oxygen
is stripped from the liquid inside the distillation column in
locations where temperature is high, e.g., in locations in the
vicinity of location 111, where heat is provided to the liquid.
Thus, where molecular oxygen remains relatively high, e.g., in
locations in the vicinity of location 118, temperature of the
organic material is sufficient low such that detrimental oxidation
of the organic material is maintained at a negligible level.
[0123] As a result of the use of a combination of (i) nitrogen
stripping, (ii) heat input to the liquid in the distillation
column, and (iii) drawing a side stream with a high water
concentration, the process and device illustrated in FIG. 1 achieve
the following. First, the removal of water and oxygen can be
effected without the use of a condenser in the vicinity of the top
of the column, resulting in significantly lower capital cost in
constructing the device. Second, the lack of a condenser also
results in a significantly lower consumption of energy in the
purification process. Third, a low temperature in the vicinity of
the top of the column, preferably close to ambient temperature, is
possible, such that the organic material in the liquid is exposed
to molecular oxygen only at a low temperature. This is particularly
beneficial for organic materials that may undergo undesirable
oxidation reaction with molecular oxygen at elevated
temperature.
[0124] Preferably, the temperature in the vicinity of the top of
the distillation column is in the vicinity of ambient temperature.
Preferably, the temperature of the crude organic liquid stream fed
into the distillation column and the temperature in the vicinity of
the top of the distillation column are both in the vicinity of
ambient temperature.
[0125] In an alternative design of a process and/or device for
removing water and/or oxygen from a crude organic liquid stream,
now shown here, similar to the design illustrated in FIG. 1, the
crude liquid stream, dry nitrogen stream and heat input are
provided to the distillation column, but a side effluent stream
rich in water is not drawn. Rather, water, nitrogen, and oxygen
exit together as a single vapor stream from a location in the
vicinity of the top of the distillation column. Because this vapor
stream typically has a relatively high temperature (e.g., higher
than ambient temperature), it can contain organic materials at a
non-negligible concentration. Thus, it is desirable to pass the
vapor stream through a condenser to obtain a liquid mixture
comprising a water phase and a liquid organic phase, which is then
delivered to a settling drum, where the liquid water phase is
separated from the liquid organic phase. The liquid organic phase
can be recycled to the distillation column, e.g., at a location in
the vicinity of the inlet of the crude liquid feed stream, and the
liquid water phase discarded as waste. Thus, a dry organic effluent
stream essentially free of oxygen can be obtained in the vicinity
of the bottom of the distillation column. In this example, water
and oxygen can be effectively removed from the crude organic liquid
stream. However, compared to the design illustrated in FIG. 1, this
design is more energy intensive, requires a condenser at the top
and is therefore more expensive, and results in exposure of the
organic material to molecular oxygen at an elevated
temperature.
[0126] While the present invention has been described and
illustrated by reference to particular embodiments, those of
ordinary skill in the art will appreciate that the invention lends
itself to variations not necessarily illustrated herein. For this
reason, then, reference should be made solely to the appended
claims for purposes of determining the true scope of the present
invention.
[0127] The contents of all references cited herein are incorporated
by reference in their entirety.
* * * * *